Polymers are used in various types of applications and often utilize a mineral filler, or extender, both to impart desired mechanical properties and to reduce raw material costs. For example, the mineral fillers typically used in polymers include calcium carbonate, kaolin, talc, mica, wollastonite, silica, glass flakes and glass spheres.
Recently, there has been an increased interest in using fly ash as a filler in polymer composites. In particular, because fly ash is a recycled material produced by the combustion of coal, fly ash qualifies as a recycled material and thus is desirable for this reason. Fly ash is also relatively inexpensive when compared to the fillers often used as fillers for polymer composites. Furthermore, it has been discovered that fly ash can be used in polymer composites without causing detriment to the mechanical properties of the polymer composites and, in many cases, improving the mechanical properties of the polymer composites.
Numerous references describe the use of fly ash in polymer composites. For example, U.S. Pat. No. 6,091,401 to Jenkines describes the use of Class F fly ash fillers in polyurethane carpet backing. Although these references describe polymer systems that can use fly ash, there is a need in the art to increase the filler loadings in polymer composites to decrease the cost of producing the polymer composites and, in many cases, to further improve the mechanical properties of the polymer composites.